FALLING ice has again shut Scotland's showpiece road bridge for the second year running - a matter of weeks after transport secretary Michael Matheson suggested lessons had been learnt.

The Queensferry Crossing connecting Edinburgh and Fife was closed to vehicular traffic in both directions at 4.45am on Friday due to "ongoing weather conditions, including falling ice and snow".  It re-opened after rush hour, having being shut for over four hours.

Transport Scotland was previously criticised for lack of action after reports of ice falling on vehicles in February

When it opened, the £1.35bn Queensferry Crossing was expected to remain open in all weather conditions.

It was fitted with 3.5m (11ft) high barriers designed to ensure the bridge would not be closed by high winds.

And at the start of last month it announced efforts to prevent the issue with ice sensors installed.

Infrastructure secretary Michael Matheson suggested the administration had learned a lesson from last winter when the crossing, which was the result of the biggest infrastructure project in Scotland in a generation, was closed following reports of ice falling on vehicles.

He had been criticised for suggesting that an earlier incident was ‘a result of a very specific set of weather conditions’ and was unlikely to recur.

Calls were made in February for an urgent investigation into ice issues on the 1.7 mile publicly funded bridge which arose 11 months after giant icicles smashed the windscreens of three cars after they snapped off from cables on the crossing.

The Herald revealed that the problem came despite the existing multi-million pound sensor system being unable to properly detect ice.

The Scottish Government were criticised for a failure to act quickly with transport secretary Michael Matheson said in October, 2019 that new sensors would be installed.

Prior to this winter season, new ice sensors were installed on the Queensferry Crossing as "part of a number of measures to improve the detection and management of ice accretion".

HeraldScotland:

The Queen opened the bridge in August, 2017.

READ MORE: Farce Road Bridge: Shut Queensferry Crossing's weather sensors cannot properly detect ice

As new measures were announced last month, Mr Matheson said: ‘Our teams always look to learn lessons from previous winters and have once again worked hard throughout the year to ensure we are well prepared for when the worst of the weather arrives.

"This ranges from the use of new technology, like ice accretion sensors and motorway access units, to trialling new treatments and adding more gritters to our fleet."

In February the crossing was closed for the first time since it opened in 2017 after ice and snow fell from cables on to vehicles below.

Eight vehicles were damaged before the bridge was closed on safety grounds.

It led to lengthy tailbacks as drivers take a 35-mile diversion, crossing the Kincardine Bridge.

At the time of the February incident, Mr Matheson said there had been a similar issue the previous winter when snow and ice built up on some of the cables, but the bridge had not been closed.

Mr Matheson said: "I recognise the frustration of travellers today, and I very much regret that the bridge has been closed for the first time, but it is a bridge that's given us much greater resilience than the old Forth Road Bridge.

"There's now been something like 30 occasions when we would have had only partial or no use of the Forth Road Bridge, whereas the Queensferry Crossing is continuing to function."

The Scottish Government then confirmed that it was planning to install ice sensors on the structure "in the coming months".

When it opened to traffic in August, 2017, it was heralded by First Minister Nicola Sturgeon as "a symbol of a confident, forward-looking Scotland" and a "feat of modern engineering".

Before it opened, bridge operators said the 3.5m high wind shields, would "almost entirely eliminate the need for closures".

Chris Tracey, Bear Scotland’s south east unit bridges manager, said: “The safety of bridge users comes first and we therefore made the decision to temporarily close the Queensferry Crossing when we identified a risk of falling ice.

“We constantly monitor conditions on the Queensferry Crossing in real time using a bespoke system of weather sensors on the towers and deck. At 04:30 this system reported conditions conducive for ice formation. Patrol staff observed ice falling from the bridge towers shortly after this and the bridge was closed at 04:45.

“The risk of falling ice has now passed and it is safe to reopen the bridge. We apologise for any inconvenience caused to road users by this closure.”

When the road was shut, Bear Scotland said ice fall was more than just a risk.

It said:  "The Queensferry Crossing is currently closed to vehicular traffic due to ongoing weather conditions, including falling ice and snow.

"All traffic is being diverted via the A985 Kincardine Bridge."

Bear Scotland said of the new detection system: “The new ice sensors on the Queensferry Crossing will not stop ice forming, however they will improve our understanding of the issue and give us some early warning when conditions are conducive to ice accretion

“The sensors monitor four weather conditions we know can cause ice accretion when they converge within specific parameters. This will help to provide early warning of such conditions and allow us to more accurately measure and understand the conditions.

“The safety of bridge users and workers comes first, so we will close the bridge and divert the traffic in conditions that cause ice accretions to form and fall from the cables.